An exhaust apparatus in a power plant and the like contains a selective catalytic reduction (SCR) catalyst which effectively removes nitrogen oxide (NOx). Typically, such a selective catalytic reduction catalyst is used for three to four years and recycled twice to three times. Thereafter, the catalyst is discarded in the form of a waste denitrification catalyst.
A waste denitrification catalyst contains valuable metals, such as vanadium (V) and tungsten (W), in the form of oxides. Generally, in the waste denitrification catalyst, vanadium oxide (V2O5) is present in an amount of about 1% by weight (wt %) to about 3 wt %, and tungsten oxide WO3 is present in an amount of about 7 wt % to about 10 wt %.
Thus, if a waste denitrification catalyst is discarded without additional use, this results in not only a burden of waste disposal costs but also loss of valuable natural resources.
However, until now, there have been few studies on recovery of valuable metals from a waste denitrification catalyst and thus such a waste denitrification catalyst has, traditionally, simply been abandoned. Therefore, there is a need for a method of recovering valuable metals from a waste denitrification catalyst.
Korean Patent Publication No. 10-2004-0067396 A (publication date: Jul. 30, 2004) discloses a method wherein a waste denitrification catalyst is treated to be used as a photocatalyst based on the fact that a large amount of titanium oxide is contained in the waste denitrification catalyst.